1. Field of the Invention
This invention relates to the production of bodies or shapes of carbides of silicon, titanium and vanadium.
Several methods of producing silicon carbide bodies are known, for example, Yamada and others in Ceramic Bulletin, Volume 64, No. 2, pages 319 to 321 (1985) describe a process in which a mixture of silicon powder and carbon powder in compacted form is held in a suitable container and is ignited on one surface to initiate reaction between silicon and carbon. The exothermic, self-sustaining reaction proceeds in a front through the mass.
Difficulties with this method include the following: It is necessary to maintain a uniform front otherwise an inferior product results; it is necessary to confine the mass; high pressure is required; and a high ignition temperature is required.
Other methods of fabrication of bodies include cold compaction to the desired shape and sintering at high temperature; deposition of an organic compound of silicon; etc. References to such prior art processes include:
S. Prochazka, "Sintering of Silicon Carbide", Materials and Coatings to Resist High Temperature Corrosion, edited by D. R. Holmes and A. Rahmel, Applied Science Publishers Ltd., England, 1978; R. A. Alliegro, "Processing and Fabrication of Non-Hot Pressed Silicon Carbide," Materials and Coatings to Resist High Temperature Corrosion, edited by D. R. Holmes and A. Rahmel, Applied Science Publishers Ltd., England, 1978; U.S. Pat. Nos. 3,495,939; 2,938,807; 2,964,823; Kennedy and Shennan, "Engineering Application of Refel Silicon Carbide, ATOM 206, pages 260-267; General Electric Company, Technical Information Series, authored by Hillig et al., entitled "Silicon/Silicon Carbide Composites"; P. Popper, "Special Ceramics" 1960, page 209 et seq., Heywood, London; and C. W. Forrest, P. Kennedy and J. V. Shennan, "The Fabrication and Properties of Ceram, Self-Bonded Silicon Carbide Bodies: Special Ceramics 5," edited by P. Popper, Brit. Ceram. Res. Assn. 1972, p. 99.
The production of solid shapes of carbides of titanium and vanadium by known methods also involve difficulties.
Another method of producing silicon carbide is described by Lubleich, U.S. Pat. No. 4,514,346, in which silicon and carbon produce silicon carbide, but in this case a binder such as novolak resin is used which does not volatize and which forms a coating on the surface of silicon and carbon particles in a coking process. This binder coke as well as carbon added as such reacts with silicon to produce SlC. A 5.degree. C./minute rate of heating, which is not considered to be rapid enough, is also used by Lubleich.
Therefore this method is not economical because it is very complicated to handle the binder when mixing with the siicon and carbon. Besides, it is not clear in Lubleich's patent whether the reaction occurs in solid phase or liquid phase whereas the reaction of the present invention occurs in liquid phase.